Ten experiments investigate the early development, in human infants, of perception of the unity of partly occluded surfaces. These experiments focus primarily on processes by which infants come to perceive objects by testing predictions drawn from an information-processing viewpoint. This perspective stresses the prior necessity of appropriate visual skills to perception of object segregation, and a time of experience viewing objects in full view and under conditions of occlusion. This experience precipitates a more thorough understanding of objects in general (the sensitivity-first hypothesis). The experiments follow a similar strategy: explorations of individual differences performance in both basic visual processing and object perception tasks. Because of the central place of motion, depth, and edge orientation in object perception, the experiments concentrate on the roles of these three cues. Performance is assessed with two methods: (a) eye tracking, to measure improvements in pickup of important visual information, and (b) habituation, both to ascertain perception of object unity and to determine the extent of sensitivity to available visual information. The short-term objectives of the experiments are to elucidate fundamental developmental mechanisms in the context of the classic nature-nurture debate. The long term goals are to shed light on the larger question of how knowledge is acquired and structured in the human, how perceptual skills impact knowledge acquisition and structure, and how to best characterize early development. In the future, such understanding may aid in the formulation of diagnostics and treatments for some developmental disorders.